1. Field of the Invention
The present invention relates to an internal power-source potential supply circuit for supplying an internal power-source potential to a predetermined load.
2. Description of the Background Art
FIG. 98 is a circuit diagram of a conventional internal power-source potential supply circuit for use in a semiconductor device. As shown, an external power-source potential VCE is applied as an internal power-source potential VCI to a load 11 through a PMOS transistor Ql. A comparator 1 has a negative input receiving a reference potential Vref and a positive input receiving the internal power-source potential VCI as a feedback signal, and provides a control signal S1 based on the result of comparison between the reference potential Vref and the internal power-source potential VCI to the gate of the PMOS transistor Q1.
In such an arrangement, if the internal power-source potential VCI is lower than the reference potential Vref, the control signal S1 from the comparator 1 has a lower potential to cause the PMOS transistor Q1 to conduct heavily. This increases the current supply capability from the external power-source potential VCE. Then, the circuit acts to raise the lowered internal power-source potential VCI. Conversely, if the internal power-source potential VCI is higher than the reference potential Vref, the control signal S1 from the comparator 1 has a higher potential to cause the PMOS transistor Q1 to conduct lightly. This stops the current supply capability from the external power-source potential VCE. Then, the circuit prevents further increase in raised internal power-source potential VCI. The comparator 1 may include a differential amplifier having a current mirror circuit or the like. In this manner, the internal power-source potential supply circuit may supply the internal power-source potential VCI equal to the reference potential Vref.
FIG. 99 is a circuit diagram of another conventional internal power-source potential supply circuit for use in a semiconductor device. As shown, the external power-source potential VCE is applied as the internal power-source potential VCI to the load 11 through the PMOS transistor Q1. The comparator 1 has a negative input receiving the reference potential Vref and a positive input receiving a divided internal power-source potential DVCI as a feedback signal.
The drain of the PMOS transistor Q1 is grounded through a resistor R11 and a resistor R12. The internal power-source potential VCI divided by the resistors R11 and R12 is applied as the divided internal power-source potential DVCI to the positive input of the comparator 1.
The circuit of FIG. 99 is advantageous in that the operating point of the comparator 1 may be freely selected, allowing the characteristics of the comparator 1 to be held satisfactory independently of the conditions set for the internal power-source potential VCI and external power-source potential VCE. In the arrangement of FIG. 98, a small difference between the external power-source potential VCE and the internal power-source potential VCI deteriorates the characteristics of the comparator 1, resulting in a delay in operation and a large amount of temporary reduction in internal power-source potential VCI.
The arrangement of FIG. 99 may supply the internal power-source potential VCI in a stable manner when the reference potential Vref is constant.
FIG. 100 is a graph indicating a drawback of the circuit of FIG. 99. In FIG. 100, (R11+R12)/R12=3/2. As shown in FIG. 100, a time interval T11 is defined during which the reference potential Vref rises to follow the varying external power-source potential VCE. During the time interval T11, the internal power-source potential VCI also rises to follow the varying external power-source potential VCE, but has a tendency to provide access to the external power-source potential VCE as the external power-source potential VCE increases. The internal power-source potential VCI grows higher than required, resulting in dangers of an increase in current consumption and a lower degree of reliability.
Additionally, the resistors R11 and R12 have fixed resistances, resulting in the fixed internal power-source potential VCI.
In this manner, the conventional internal power-source potential supply circuits are disadvantageous in that variations in the external power-source potential may cause decreased performance of the circuit, finding difficulties in supplying the internal power-source potential with high accuracy.
A first aspect of the present invention is intended for an internal power-source potential supply circuit for supplying an internal power-source potential to a predetermined load. According to the present invention, the internal power-source potential supply circuit comprises: internal power-source potential applying means having a first end receiving an external power-source potential, and a second end for applying the internal power-source potential to the predetermined load in response to a control signal; a resistor element having a first end connected to the second end of the internal power-source potential applying means; current supply means for supplying a predetermined current to between a second end of the resistor element and a fixed potential; and a comparator circuit for receiving a divided internal power-source potential from the second end of the resistor element and a reference potential to output the control signal on the basis of a comparison result between the divided internal power-source potential and the reference potential.
Preferably, according to a second aspect of the present invention, the resistor element receives a resistor control signal and has a resistance varied in response to the resistor control signal.
Preferably, according to a third aspect of the present invention, the internal power-source potential supply circuit further comprises: a control circuit for outputting the resistor control signal on the basis of an environmental condition including temperature change.
Preferably, according to a fourth aspect of the present invention, the resistor element comprises a plurality of partial resistive elements connected in series between the first and second ends of the resistor element, and the internal power-source potential supply circuit further comprises: resistor selecting means provided in at least one of the plurality of partial resistive elements for selecting enablement/disablement of the at least one partial resistive element.
Preferably, according to a fifth aspect of the present invention, the current supply means comprises first partial current supply means for supplying a first partial current to between the second end of the resistor element and the fixed potential, and second partial current supply means for supplying a second partial current to between the second end of the resistor element and the fixed potential when being active, the second partial current supply means receiving a current control signal, the second partial current supply means being active/inactive in response to the current control signal.
Preferably, according to an sixth aspect of the present invention, the current supply means comprises first partial current supply means for supplying a first partial current to between the second end of the resistor element and the fixed potential, and second partial current supply means for supplying a second partial current to between the external power-source potential and the second end of the resistor element when being active, the second partial current supply means receiving a current control signal, the second partial current supply means being active/inactive in response to the current control signal.
Preferably, according to a seventh aspect of the present invention, the comparator circuit is active/inactive in response to a circuit control signal indicative of an active/inactive state, and the internal power-source potential supply circuit further comprises switching means on a current path extending from the second end of the internal power-source potential applying means to the fixed potential for cutting off the current path when being non-conducting, the switching means being conducting/non-conducting in response to the circuit control signal indicative of the active/inactive state.
Preferably, according to a eighth aspect of the present invention, the internal power-source potential supply circuit further comprises reference potential setting means for receiving a reference potential control signal to set the reference potential in response to the reference potential control signal.
Preferably, according to an ninth aspect of the present invention, the internal power-source potential supply circuit further comprises: an external terminal; and switching means having a first end receiving as a monitor potential one of the divided internal power-source potential, the reference potential, and the internal power-source potential, and a second end connected to the external terminal, the switching means further receiving a selection signal, the switching means being on/off in response to the selection signal.
Preferably, according to a tenth aspect of the present invention, the internal power-source potential supply circuit further comprises second switching means having a first end receiving a predetermined signal, and a second end connected to the external terminal, the second switch means being off/on when the switching means is on/off, respectively.
Preferably, according to a eleventh aspect of the present invention, the external terminal is connected to an input of a predetermined circuit.
Preferably, according to a twelfth aspect of the present invention, the internal power-source potential supply circuit further comprises second internal power-source potential applying means for receiving an internal power-source potential control signal, the second internal power-source potential applying means being active to apply the external power-source potential as the internal power-source potential to the predetermined load when the internal power-source potential control signal indicates an active state.
Preferably, according to a thirteenth aspect of the present invention, the comparator circuit comprises at least one transistor; a plan structure of the at least one transistor includes an active region, and a control electrode region at least partially provided on the active region and having first and second partial control electrode regions spaced a predetermined distance apart from each other in a predetermined direction so that a part of the active region which is located between the first and second partial control electrode regions is defined as a first electrode region and so that parts of the active region which are located on the opposite side of the first and second partial control electrode regions from the first electrode region are defined as second and third electrode regions, respectively; and the control electrode region, and the first, second and third electrode regions form the at least one transistor.
A fourteenth aspect of the present invention is intended for an internal power-source potential supply circuit for supplying an internal power-source potential to a predetermined load. According to the present invention, the internal power-source potential supply circuit comprises: first internal power-source potential applying means having a first end receiving an external power-source potential, and a second end for applying the internal power-source potential to the predetermined load in response to a control signal; a comparator circuit for receiving the internal power-source potential and a reference potential to output the control signal on the basis of a comparison result between the internal power-source potential and the reference potential; external power-source potential determining means for receiving the external power-source potential to output an external power-source potential determination signal indicative of an active/inactive state in response to the external power-source potential; and second internal power-source potential applying means for receiving the external power-source potential determination signal to forcibly apply the external power-source potential as the internal power-source potential to the predetermined load when the external power-source potential determination signal indicates the active state.
A fifteenth aspect of the present invention is intended for an internal power-source potential supply circuit for supplying an internal power-source potential to a predetermined load. According to the present invention, the internal power-source potential supply circuit comprises: an internal power-source potential applying means having a first end receiving a first external power-source potential, and a second end for applying the internal power-source potential to the predetermined load in response to a control signal; and a comparator circuit for receiving the internal power-source potential and a reference potential to output the control signal on the basis of a comparison result between the internal power-source potential and the reference potential, the comparator circuit further receiving a second external power-source potential difference from the first external power-source potential to use the second external power-source potential as a drive power-source potential.
Preferably, according to an sixteenth aspect of the present invention, the second external power-source potential is higher than the first external power-source potential.
Preferably, according to a seventeenth aspect of the present invention, the second external power-source potential is provided independently of the first external power-source potential.
A eighteenth aspect of the present invention is intended for an internal power-source potential supply circuit for supplying an internal power-source potential to a predetermined load. According to the present invention, the internal power-source potential supply circuit comprises: first internal power-source potential supply means; and second internal power-source potential supply means, the first internal power-source potential supply means including internal power-source potential applying means having a first end receiving an external power-source potential, and a second end for providing a first internal power-source potential in response to a first control signal, a first resistor element having a first end connected to the second end of the first internal power-source potential applying means, first current supply means for supplying a first current to between a second end of the first resistor element and a fixed potential, a first comparator circuit receiving a first divided internal power-source potential provided from the second end of the first resistor element and a first reference potential, the first comparator circuit being active/inactive in response to a circuit control signal indicative of an active/inactive state, the first comparator circuit outputting the first control signal on the basis of a comparison result between the first divided internal power-source potential and the first reference potential when being active, and switching means on a current path extending from the second end of the first internal power-source potential applying means to the fixed potential for cutting off the current path when being non-conducting, the switching means being conducting/non-conducting in response to the circuit control signal indicative of the active/inactive state, the second internal power-source potential supply means including second internal power-source potential applying means having a first end receiving the external power-source potential, and a second end for providing a second internal power-source potential in response to a second control signal, a second resistor element having a first end connected to the second end of the second internal power-source potential applying means, second current supply means for supplying a second current to between a second end of the second resistor element and the fixed potential, and a second comparator circuit for receiving a second divided internal power-source potential provided from the second end of the second resistor element and a second reference potential to output the second control signal on the basis of a comparison result between the second divided internal power-source potential and the second reference potential, the first internal power-source potential and the second internal power-source potential being synthesized to provide an internal power-source potential to the predetermined load.
Preferably, according to a nineteenth aspect of the present invention, the first resistor element of the first internal power-source potential supply means has a resistance varied in response to a resistor control signal.
Preferably, according to a twentieth aspect of the present invention, the first current supply means comprises first partial current supply means for supplying a first partial current to between the second end of the first resistor element and the fixed potential, and second partial current supply means for supplying a second partial current to between the second end of the first resistor element and the fixed potential when being active, the second partial current supply means receiving a current control signal, the second partial current supply means being active/inactive in response to the current control signal.
According to a twenty-first aspect of the present invention, a step-up potential generating system comprises: reference potential generating means for generating a reference potential based on an internal power-source potential from an internal power-source potential supply circuit as recited in claim 1; step-up potential generating means for generating a step-up potential in response to a control signal; voltage-dividing means for dividing the step-up potential to output a divided step-up potential; limit potential generating means for generating a fixed limit potential; first comparator means for comparing the divided step-up potential with the reference potential to output a first comparison result; second comparator means for comparing the divided step-up potential with the limit potential to output a second comparison result; and control signal output means receiving the first and second comparison results, the control signal output means outputting the control signal in response to the first comparison result when the second comparison result indicates that the divided step-up potential is lower than the limit potential, the control signal output means outputting the control signal in response to the second comparison result when the second comparison result indicates that the divided step-up potential is higher than the limit potential.
Preferably, according to a twenty-second aspect of the present invention, the internal power-source potential supply circuit further comprises: reference potential setting current supply means having a first end receiving the external power-source potential and a second end for providing a predetermined current; a reference potential setting resistor element having a first end connected to the second end of the reference potential setting current supply means and a second end connected to the fixed potential, the reference potential setting resistor element including a plurality of reference potential setting partial resistive elements connected in parallel between the first and second ends of the reference potential setting resistor element; and reference potential setting resistor selecting means corresponding to at least one of the reference potential setting partial resistive elements for selecting enablement/disablement of the at least one reference potential setting partial resistive element, wherein a potential at the first end of the reference potential setting resistor element is applied as the reference potential to the comparator circuit.
According to a twenty-third aspect of the present invention, an internal power-source potential supply circuit for supplying an internal power-source potential to at least one load, comprises: internal power-source potential applying means having a first end receiving an external power-source potential, and a second end for applying the internal power-source potential to the at least one load in response to a control signal; comparison potential selecting means for receiving an associated internal power-source potential associated with the internal power-source potential fed from the internal power-source potential applying means and an associated load potential associated with the at least one load to output one of the associated internal power-source potential and the associated load potential which has a smaller potential difference from a fixed potential as a comparison potential; and a comparator circuit for receiving the comparison potential and a reference potential to output the control signal on the basis of a comparison result between the comparison potential and the reference potential.
Preferably, according to a twenty-fourth aspect of the present invention, the at least one load includes first and second loads, and the internal power-source potential supply circuit further comprises: a first resistor element corresponding to the first load and having a first end connected to the second end of the internal power-source potential applying means; first current supply means corresponding to the first load for supplying a predetermined current to between a second end of the first resistor element and the fixed potential; a second resistor element corresponding to the second load and having a first end connected to the second end of the internal power-source potential applying means, the second resistor element having the same resistance as the first resistor element; and second current supply means corresponding to the second load for supplying the predetermined current to between a second end of the second resistor element and the fixed potential, the associated internal power-source potential including a first divided internal power-source potential provided at the second end of the first resistor element, the associated load potential including a second divided internal power-source potential provided at the second end of the second resistor element.
Preferably, according to a twenty-fifth aspect of the present invention, the associated internal power-source potential includes an output-time associated internal power-source potential associated with a potential at the second end of the internal power-source potential supply means, and the associated load potential includes a practical associated load potential associated with a potential practically received by the at least one load.
Preferably, according to a twenty-sixth aspect of the present invention, the internal power-source potential supply circuit further comprises current control means for controlling the amount of the predetermined current on the basis of a practical load potential which is a potential practically received by the predetermined load.
According to a twenty-seventh aspect of the present invention, a semiconductor memory having a memory cell formed on a semiconductor substrate, comprises an internal power-source potential supply circuit for supplying an internal power-source potential to a predetermined load, the internal power-source potential supply circuit including: internal power-source potential applying means having a first end receiving an external power-source potential, and a second end for applying the internal power-source potential to the predetermined load in response to a control signal; a resistor element having a first end connected to the second end of the internal power-source potential applying means; current supply means for supplying a predetermined current to between a second end of the resistor element and a fixed potential; and a comparator circuit for receiving a divided internal power-source potential from the second end of the resistor element and a reference potential to output the control signal on the basis of a comparison result between the divided internal power-source potential and the reference potential, the resistor element receiving a resistor control signal and having a resistance varied in response to the resistor control signal, the semiconductor memory receiving the internal power-source potential at a first level during a normal operation, the semiconductor memory receiving the internal power-source potential at a second level having a greater potential difference from a substrate potential of the semiconductor substrate than the first level to perform a write operation by using the internal power-source potential at the second level during a write operation.
Preferably, according to a twenty-eighth aspect of the present invention, the semiconductor memory, further comprises: a sense amplifier for detecting and amplifying a potential read from a memory cell during a read operation, the sense amplifier operating at a first current during a normal read operation and operating at a second current during a special read operation, the second current being less in amount than the first current.
Preferably, according to a twenty-ninth aspect of the present invention, the semiconductor memory, further comprises: a substrate potential generating circuit for generating a substrate potential to be applied to the semiconductor substrate, the substrate potential generating circuit providing the substrate potential at the first level during a normal read operation and generating the substrate potential at the second level during a special read operation, the second level being closer to the internal power-source potential than the first level.
The internal power-source potential supply circuit of the first aspect of the present invention comprises the resistor element having the first end connected to the second end of the internal power-source potential applying circuit, and the current supply means for supplying the predetermined current to between the second end of the resistor element and the fixed potential. Thus, the potential difference between the divided internal power-source potential and the internal power-source potential is determined by the resistance of the resistor element and the amount of predetermined current without being affected by fluctuation in external power-source potential.
The result is stable supply of the internal power-source potential independently of fluctuation in external power-source potential. This achieves supply of the internal power-source potential with high accuracy.
The resistor element of the second aspect of the present invention has a resistance varied in response to the resistor control signal. The resistance of the resistor element may be varied to vary the internal power-source potential.
The internal power-source potential supply circuit of the third aspect of the present invention further comprises the control circuit for outputting the resistor control signal on the basis of environmental conditions such as temperature changes. The resistance of the resistor element may be varied in accordance with changes in environmental conditions. This permits the internal power-source potential to be varied in accordance with changes in environmental conditions.
The resistor element in the internal power-source potential supply circuit of the fourth aspect of the present invention comprises the plurality of partial resistive elements, and the internal power-source potential supply circuit comprises the resistor selecting means provided in at least one of the plurality of partial resistive elements for selecting the enablement/disablement of the at least one partial resistive element. Thus, the resistance of the resistor element may be varied by selection of the resistor selecting means to vary the internal power-source potential.
The current supply means in the internal power-source potential supply circuit of the fifth aspect of the present invention comprises the first partial current supply means for supplying the first partial current to between the second end of the resistor element and the fixed potential, and the second partial current supply means which is active/inactive in response to the current control signal for supplying the second partial current to between the second end of the resistor element and the fixed potential when being active. The control of the active/inactive state of the second partial current supply means may control the increase/decrease in the amount of current flowing through the resistor element to vary the internal power-source potential.
The current supply means in the internal power-source potential supply circuit of the sixth aspect of the present invention comprises the first partial current supply means for supplying the first partial current to between the second end of the resistor element and the fixed potential, and the second partial current supply means which is active/inactive in response to the current control signal for supplying the second partial current to between the external power-source potential and the second end of the resistor element when being active. The control of the active/inactive state of the second partial current supply means may control the decrease/increase in the amount of current flowing through the resistor element to vary the internal power-source potential.
The internal power-source potential supply circuit of the seventh aspect of the present invention comprises the comparator circuit which is active/inactive in response to the circuit control signal, and the switching means formed on the current path extending between the second end of the internal power-source potential applying means and the fixed potential. The switching means is conducting/non-conducting in response to the circuit control signal indicative of the active/inactive state, and cuts off the current path when being non-conducting. If the circuit control signal indicates the inactive state, the switching means cuts off the current path extending between the second end of the internal power-source potential applying means and the fixed potential to prevent a short circuit current to flow in the current path.
The internal power-source potential supply circuit of the eighth aspect of the present invention comprises the reference potential setting means for setting the reference potential in response to the reference potential control signal. The reference potential may be varied to vary the internal power-source potential.
The internal power-source potential supply circuit of the ninth aspect of the present invention comprises the switching means having the first end receiving the monitor potential which is one of the divided internal power-source potential, the reference potential, and the internal power-source potential, and the second end connected to the external terminal. If the switching means is in the ON position, the monitor potential may be outputted to the exterior through the external terminal.
The internal power-source potential supply circuit of the tenth aspect of the present invention further comprises the second switching means which is in the ON position to output the predetermined signal to the external terminal when the switching means is in the OFF position. If the switching means is in the OFF position, the predetermined signal may be outputted to the external terminal.
In the internal power-source potential supply circuit of the eleventh aspect of the present invention, the external terminal is connected to the input of the predetermined circuit. If the switching means is in the OFF position, the external signal may be applied to the input of another internal circuit.
The internal power-source potential supply circuit of the twelfth aspect of the present invention further comprises the second internal power-source potential applying means which is active to apply the external power-source potential as the internal power-source potential to the predetermined load when the internal power-source potential control signal indicates the active state. The internal power-source potential may be set to the external power-source potential as required.
The comparator circuit in the internal power-source potential supply circuit of the thirteenth aspect of the present invention includes at least one transistor having the plane structure which comprises the control electrode regions at least partially formed on the active region and having the first and second partial control electrode regions spaced the predetermined distance apart form each other in the predetermined direction. The part of the active region which is located between the first and second partial control electrode regions is defined as the first electrode region, and the parts of the active region which are located on opposite side of the first and second partial control electrode regions from the first electrode region are defined as the second and third electrode regions, respectively. The control electrode region, and the first, second, and third electrode regions form the at least one transistor.
The at least one transistor is equivalent to an in-series connection of a first partial transistor including the second electrode region, the first partial control electrode region, and the first electrode region and a second partial transistor including the third electrode region, the second partial control electrode region, and the first electrode region, both of which are arranged in the predetermined direction, with the gate shared between the first and second partial transistors.
If mask misalignment might cause deviation of the contact position for wiring relative to the first, second, and third electrode regions in the predetermined direction, the deviation is canceled between the first and second partial transistors, preventing changes in performance of the at least one transistor.
Consequently, the accurate transistor may form the comparator circuit. Thus, the comparator may be formed with high accuracy.
The internal power-source potential supply circuit of the fourteenth aspect of the present invention comprises the second internal power-source potential applying means for forcibly applying the external power-source potential as the internal power-source potential to the predetermined load when the external power-source potential determination signal indicates the active state. If the external power-source potential is in a predetermined state, the internal power-source potential may be forcibly set to the external power-source potential to suppress the fluctuation in internal power-source potential.
In the internal power-source potential supply circuit of the fifteenth aspect of the present invention, the comparator circuit further receives the second external power-source potential different from the first external power-source potential to use the second external power-source potential as the drive power-source potential. The internal power-source potential supply circuit may receive the second external power-source potential which is suitable for the operation of the comparator circuit.
For example, as in the internal power-source potential supply circuit of the sixteenth aspect of the present invention, the second external power-source potential may be higher than the first external power-source potential, achieving the high-speed operation of the comparator circuit.
Alternatively, as in the internal power-source potential supply circuit of the seventeenth aspect of the present invention, the second external power-source potential may be provided independently of the first external power-source potential. This allows the operation of the comparator circuit without being affected by the internal power-source potential applying means.
The internal power-source potential supply circuit of the eighteenth of the present invention comprises the first internal power-source potential supply means which may be selectively active/inactive, and the second internal power-source potential supply means.
Depending on the conditions, the first internal power-source potential supply means may be inactivated to cause only the second internal power-source potential supply means to supply the internal power-source potential, or the first internal power-source potential supply means may be activated to cause the first and second internal power-source potential supply means to supply the internal power-source potential.
In the internal power-source potential supply circuit of the nineteenth aspect of the present invention, the first resistor element of the first internal power-source potential supply means has the resistance varied in response to the resistor control signal. Thus, the resistance of the first resistor element may be varied to vary the first internal power-source potential.
In the internal power-source potential supply circuit of the twentieth aspect of the present invention, the first current supply means of the first internal power-source potential supply means includes the first partial current supply means for supplying the first partial current to between the second end of the first resistor element and the fixed potential, and the second partial current supply means which is active/inactive in response to the current control signal for supplying the second partial current to between the second end of the first resistor element and the fixed potential when being active. The control of the active/inactive state of the second partial current supply means may control the increase/decrease in the amount of current flowing through the first resistor element to vary the first internal power-source potential.
The step-up potential generating system of the twenty-first aspect of the present invention comprises the first comparator means for comparing the divided step-up potential with the reference potential based on the internal potential to output the first comparison result, the second comparator means for comparing the divided step-up potential with the limit potential to output the second comparison result, and the control signal output means which outputs the control signal in response to the first comparison result when the second comparison result indicates that the divided step-up potential is lower than the limit potential and which outputs the control signal in response to the second comparison result when the second comparison result indicates that the divided step-up potential is higher than the limit potential.
Thus, this system performs control such that the step-up potential is higher than the internal power-source potential by the amount of predetermined level until the divided step-up potential exceeds the limit potential, and such that the step-up potential is set so that the divided step-up potential equals the limit potential independently of the variations in the internal power-source potential when the divided step-up potential exceeds the limit potential.
As a result, the step-up potential generating system of the twenty-first aspect of the present invention may generate the step-up potential varied in accordance with the variations in the internal power-source potential within such a range that the step-up potential does reach its upper limit, while positively suppressing the upper limit of the step-up potential.
In accordance with the internal power-source potential supply circuit of the twenty-second aspect of the present invention, the reference potential setting resistor selecting means corresponds to at least one of the plurality of reference potential setting partial resistive elements and selects enablement/disablement of the at least one reference potential setting partial resistive element to provide the potential at the first end of the reference potential setting resistor element as the reference potential to the comparator circuit. The selection of the reference potential setting resistor selecting means may vary the reference potential to vary the internal power-source potential.
In accordance with the internal power-source potential supply circuit of the twenty-third aspect of the present invention, the comparison potential selecting means receives the associated internal power-source potential associated with the internal power-source potential fed from the internal power-source potential applying means and the associated load potential associated with at least one load to output one of the associated internal power-source potential and associated load potential which has a smaller potential difference from the fixed potential as the comparison potential. The comparator circuit outputs the control signal on the basis of the comparison result between the comparison potential and the reference potential.
Thus, the internal power-source potential may be determined on the basis of one of the associated internal power-source potential and associated load potential which has a smaller potential difference from the fixed potential and which is more required to be controlled.
In accordance with the internal power-source potential supply circuit of the twenty-fourth aspect of the present invention, the associated internal power-source potential includes the first divided internal power-source potential provided at the second end of the first resistor element and corresponding to the first load, and the associated load potential includes the second divided internal power-source potential provided at the second end of the second resistor element and corresponding to the second load. The internal power-source potential may be determined on the basis of one of the first and second divided internal power-source potentials which has a smaller potential difference from the fixed potential and which is more required to be controlled.
In accordance with the internal power-source potential supply circuit of the twenty-fifth aspect of the present invention, the associated internal power-source potential includes the output-time associated internal power-source potential associated with the potential at the second end of the internal power-source potential supply means, and the associated load potential includes the practical associated load potential associated with the potential practically received by the at least one load. The internal power-source potential may be determined on the basis of one of the output-time associated internal power-source potential and the practical associated load potential which has a smaller potential difference from the fixed potential and which is more required to be controlled.
The internal power-source potential supply circuit according to the twenty-sixth aspect of the present invention further comprises the current control means for controlling the amount of the predetermined current on the basis of the practical load potential which is the potential practically received by the predetermined load. The amount of the predetermined current may be varied on the basis of the practical load potential, varying the internal power-source potential.
The semiconductor memory of the twenty-seventh aspect of the present invention receives the internal power-source potential at the second level having a greater potential difference from the substrate potential of the semiconductor substrate than the first level during the write operation to perform the write operation by using the internal power-source potential. This prolongs the time period over which the storage node potential changes toward the substrate potential by the leak current to reach the insensitive region, thereby improving the retention characteristic of the memory cell.
In accordance with the semiconductor memory of the twenty-eighth aspect of the present invention, the sense amplifier operates at the first current during the normal read operation and operates at the second current which is less in amount than the first current during the special read operation. Thus, the sense amplifier exhibits a more sensitive sense function during the special read operation than does during the normal read operation. As a result, the retention characteristic of the memory cell may be improved.
In accordance with the semiconductor memory of the twenty-ninth aspect of the present invention, the substrate potential generating circuit provides the substrate potential at the first level during the normal read operation, and generates the substrate potential at the second level which is closer to the internal power-source potential than the first potential during the special read operation. This decreases the degree of variation in storage node potential toward the substrate potential by the leak current to prolong the time period over which the storage node potential reaches the insensitive region. Consequently, the retention characteristic of the memory cell may be improved.
It is therefore an object of the present invention to provide an internal power-source potential supply circuit which is capable of accurately or variably supplying an internal power-source potential.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.